Fuel level sensors are known for detecting the fuel level in gasoline tanks of automobiles. Generally, the fuel level sensors include a float that is connected to a contact member by an appropriate connecting structure. The contact member is mounted in relation to a resistor card that generally includes a conductive ink or layer for forming an electrical circuit with the contact member. As the level of fuel within a tank changes, the float member moves thereby causing the contact to move along a predefined path with respect to the resistor card which then sends a signal to a fuel level indicator.
In use, fuel level sensors generally known in the art, can fail as a result of either the contacts or the conductive ink contained on the resistor card reacting with the liquid fuel or byproducts or additives contained within the liquid fuel. In an effort to combat the failure of fuel level sensors, various manufacturers have designed contacts and resistors that include materials having an increased durability in the presence of a hostile fuel tank environment. Included in these materials are expensive precious metals such as platinum, gold, silver, and palladium, which can be combined into alloys that display increased corrosion resistance in a fuel environment. The cost of using such expensive alloy materials greatly contributes to the overall cost of a fuel level sensor.
In recent years, increased environmental legislation has resulted in gasoline and diesel hydrocarbon fuel formulations that vary geographically, as to their overall composition. For example, recent legislation has sought to reduce the sulfur content contained in automotive fuels by removing sulfur containing compounds, thus leaving behind residual traces of highly reactive sulfur compounds. These sulfur compounds are known to react with the precious metals contained in contacts or conductive inks, to form nonconducting deposits that may lead to sensor failure. Due to the ongoing environmental legislation, various fuel compositions unknown at this time could lead to failures in fuel sensors by the above-recited mechanisms.